A reaction between species A and B is carried out in aqueous solution at 20 °C. The concentration of B is maintained at a constant 1.0 M throughout the experiment, while the concentration of A is monitored over time. The data are given below.
Time (s)
[A] (M)
0
0.040
50
0.032
100
0.025
150
0.019
200
0.015
250
0.012
(a) Determine the overall order of the reaction with respect to A under the experimental conditions. Support your answer with appropriate analysis of the data.
(b) Calculate the numerical value and units of the observed rate constant kobs for this reaction.
(c) At the same temperature, the experiment is repeated with an initial concentration of A equal to 0.060 M (B still at 1.0 M). Predict the concentration of A after 200 s, assuming the same rate law applies.
(d) Explain why maintaining a large, effectively constant concentration of B simplifies the kinetic analysis of this reaction.